I have built post and beam conventional joist stacked sub floor. I have built many on retaining walls as well. I would think it would depend on the area you live and the plans drawn for the project.
In the San Francisco Bay Area, we have built many pier and grade beam foundations on hillsides.
- Rhoda Fry http://www.billfryconstruction.com/
The foundation design is determined by a number of factors.
#1 Soil Conditions. These can only be determined by a soils investigation (geologist or soils engineer). Though the surface soils may look similar, the underlying strata can vary significantly in the same neighborhood, even on the SAME PARCEL! You cannot determine the required foundation type by merely looking at the site. Borings and analysis need to be performed to determine the load bearing capacity, if it is a cut & fill lot and the soil’s stability. Even a flat lot, may require expensive pile foundations if the soil is unstable or highly expansive.
Anyone who designs or specifies a foundation without referring to a soils report is assuming the liability for that structure - because the International Building Code (IBC) and the CA Building Code (CBC) both mandate that structures be designed and built to withstand the surcharges placed upon them and any site conditions (soils are part of the site conditions!).
#2 Degree of the slope. Depending on the slope of the lot, foundations may need to be deepened to achieve the required set-back to the face of the slope. The steeper the slope, the deeper the foundation must be founded, in order to achieve the mandated setbacks.
#3 Building Codes - Both the IBC and the CBC specify precise setbacks from the face of a slope. Some sites are so steep that they are unbuildable without extensive caissons, gradebeams and tiebacks.
#4 Structural Load - The bigger the building the larger and deeper the foundation. Example: a highrise office building’s deep foundation requirements.
Step down foundation with grade beams
the answer by aquatic tech just about sums it up… hillside foundation design depends on the type of soil, the degree of the slope and the building codes. in addition, it would also depend on the design of the house, the depth of load bearing soil, as well as the stability of the surrounding slope.
For making home at the hillside we must take care on following points like
Climate, Soil condition, depending on how the slope is situated,
Hillside home plans are most often two or two and a half stories.